Orphan drugs and forking paths: I’d prefer a multilevel model but to be honest I’ve never fit such a model for this sort of problem

December 3, 2017
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(This article was originally published at Statistical Modeling, Causal Inference, and Social Science, and syndicated at StatsBlogs.)

Amos Elberg writes:

I’m writing to let you know about a drug trial you may find interesting from a statistical perspective.

As you may know, the relatively recent “orphan drug” laws allow (basically) companies that can prove an off-patent drug treats an otherwise untreatable illness, to obtain intellectual property protection for otherwise generic or dead drugs. This has led to a new business of trying large numbers of combinations of otherwise-unused drugs against a large number of untreatable illnesses, with a large number of success criteria.

Charcot-Marie-Tooth (CMT) is a moderately rare genetic degenerative peripheral nerve disease with no known treatment. CMT causes the Schwann cells, which surround the peripheral nerves, to weaken and eventually die, leading to demyelination of the nerves, a loss of nerve conduction velocity, and an eventual loss of nerve efficacy.

PXT3003 is a drug currently in Phase 2 clinical testing to treat CMT. PXT3003 consists of a mixture of low doses of baclofen (an off-patent muscle relaxant), naltrexone (an off-patent medication used to treat alcoholism and opiate dependency), and sorbitol (a sugar substitute.)

Pre-phase 2 results from PXT3003 are shown here.

I call your attention to Figure 2 [above], and note that in Phase 2, efficacy will be measured exclusively by the ONLS score.

My reply: 33 comparisons, 4 are statistically significant: much more than the 1.65 that would be expected by chance alone, so what’s the problem??

In all seriousness, I’d recommend they fit a multilevel model. That said, I’ve never fit such a model for this sort of experiment. I’d like to do it (at least) once, for a live example, as I think this would help me better understand the statistical issues and then I’d be able to make more helpful recommendations.

The post Orphan drugs and forking paths: I’d prefer a multilevel model but to be honest I’ve never fit such a model for this sort of problem appeared first on Statistical Modeling, Causal Inference, and Social Science.



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